title: [Bitemporal hemianopia as presenting sign of severe ethambutol toxicity].
abstract: BACKGROUND
  Optic neuropathy is a severe and well-known complication of ethambutol treatment. If not detected early, it may lead to profound and irreversible vision loss.
  
  
  METHODS
  We report the case of a 83-year-old female patient, referred for rapidly progressive, painless, bilateral visual loss, unimproved after bilateral cataract surgery. Automated Humphrey 24-2 visual field demonstrated bitemporal hemianopia associated with bilateral central scotoma. Brain MRI did not demonstrate any compressive lesion in the chiasmal region. However, on T2-weighted sequences, an area of elevated signal intensity appeared within the optic chiasm, enhancing after gadolinium injection. On detailed history, it was noted that the patient had been on ethambutol for the last 18months, for the treatment of a Mycobacterium avium-related pneumonitis.
  
  
  CONCLUSIONS
  The incidence of ethambutol-related toxic optic neuropathy has dramatically decreased since the recommendations for regular follow-up of patients treated with ethambutol. This treatment is classically responsible for bilateral central or ceco-central scotoma due to optic neuropathy, although a few cases of bitemporal hemianopia have been reported in the literature, mimicking a compressive chiasmal lesion. However, none of these cases demonstrated a hypersignal in the optic chiasm on brain magnetic resonance imaging (MRI).
  
  
  CONCLUSIONS
  Bitemporal hemianopia on visual field testing is very suggestive of a chiasmal lesion, which is generally due to a compressive, or more rarely inflammatory, lesion in the sellar region. Toxic chiasmal lesions are rare, but in the absence of any tumoral lesion in the sellar area, a detailed history must be obtained in order to rule out drug toxicity, so as to prevent irreversible visual loss.
authors.affiliation: Service d'ophtalmologie, hôpital Pitié-Salpêtrière, 47-83, boulevard de l'Hôpital, 75013 Paris, France.
authors.forename: E
authors.initials: E
authors.lastname: Boulanger Scemama
authors.forename: V
authors.initials: V
authors.lastname: Touitou
authors.forename: P
authors.initials: P
authors.lastname: Le Hoang
mesh_terms: D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000009:adverse effects*; D003937:Diagnosis, Differential; D064420:Drug-Related Side Effects and Adverse Reactions / Q000175:diagnosis*; D004977:Ethambutol / Q000009:adverse effects*; D005260:Female; D006423:Hemianopsia / Q000139:chemically induced* / Q000175:diagnosis*; D006801:Humans; D009162:Mycobacterium avium; D012720:Severity of Illness Index; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy
chemical_list: D000995:Antitubercular Agents; D004977:Ethambutol
keywords: Bitemporal hemianopia; Ethambutol; Hémianopsie bitemporale; Neuropathie optique; Optic neuropathy; Toxicity; Toxicité; Éthambutol